For the past a few years, there have been introduced various kinds of display devices in the aspect of shapes and functions, etc., and various portable display devices are also being developed. However, in case of a portable display device, the image displayed on its display unit may look tilted according to the installation direction of the portable display device. To comply with a request to solve the disadvantage, there is introduced a display product, in which a user can select and change the display direction of the image displayed on its display unit manually as shown in FIG. 1 to compensate for a rotation angle of the image as much as the image display unit is tilted.
FIG. 1 is a block diagram schematically showing the structure of a conventional display device.
With reference to FIG. 1, a conventional display device includes a user input unit 110 for receiving a control instruction input by a user, a control unit 120 for processing a control signal transmitted from the user input unit 110, an image display control unit 130 for processing an image signal (brightness, resolution, display size, etc.) to be displayed on a display screen according to a signal transmitted from the control unit 120, an image display unit 150 for displaying a signal transmitted from the image display control unit 130, and an image display memory 140 for storing information to be displayed on the image display unit 150.
The control unit 120 includes a microcomputer 121 for generally controlling the whole operation of the device, an input/output control unit 123 for processing a communication between the microcomputer 121 and the image display control unit 130, and a control unit memory 122 for storing a particular form of information which is necessary in the control unit 120.
Next, there will be illustrated a method of processing the display image according to the control instructions from a user in the display device structured as above.
If a user wants to compensate for the tilted angle of the image displayed on the image display unit 150 as much as the display device is tilted, a control instruction to change the image display direction should be inputted through the user input unit 110.
Accordingly, the control instruction input to the user input unit 110 by a user is transmitted to the control unit 120, and the input/output control unit 123 of the control unit 120 transmits the control signal of the compensated information in the form of a data signal (DATA), a clock signal (CLK), and an enable signal (EN) to the image display control unit 130.
The DATA, CLK and EN to be used are communication protocols to control the image display control unit 130.
In more detail, the enable signal (EN) is output in a high state (HIGH) when communicating with the image display control unit 130. As such, the image display control unit 130 can accept the signal even if the enable signal (EN) in a high state (HIGH) sends the DATA and CLK signals.
Then, after the communication is completed, the EN is converted into a low state (LOW) again, and the transmission of the control signal is completed.
Here, the DATA consists of the values of address and registers which the image display control unit 130 should actually control, and the CLK is used for synchronization when the data output is executed.
The image display control unit 130, which receives the control signal transmitted from the control unit 120, calculates the compensation of the image information input through the user input unit 110 by a user, and converts and stores the information for the display into the image display memory 140. Then, the data stored in the image display memory 140 is displayed through the image display unit 150.
In view of the above to take an example, in case that a user wants to see the image on the display screen in an opposite direction with the display device turned upside down, he or she should select the function mode to change the image display direction by using the user input unit 110 such as a remote controller or a panel of the display device, and choose an ‘inversion’ mode for the image display direction. Then, the control unit 120 extracts the register values related with the inversion of the display screen of the image display control unit 130 to make the image display direction inverse.
The data of the extracted values is transmitted from the control unit 120 through DATA, CLK and EN to the each of the registers of the image display control unit 130. Accordingly, the image display control unit 130 stores the image signal input according to the change of the register values into the image display memory 140 by changing as a digital value.
Then, since the stored values are stored in a manner that the start portion of the displayed image is stored from the end portion of the image display memory 140, the image is not displayed inversely even if the image display unit 150 is turned upside down, and accordingly, when a user sees the image through the image display unit 150, the image is displayed in a normal direction without inversion.
FIG. 2(a) illustrates a state that the image is displayed when the conventional image display unit is placed in a normal direction, and FIG. 2(b) illustrates a state that the image is displayed when the conventional image display unit is placed inversely.
In addition, the direction of the arrows on the drawings indicates the upper side of the image display unit 150.
As described above, the state that the upside and the downside of the image display unit 150 of the display device are exchanged, that is, the state that the image display unit 150 is placed inversely, a user should reset the image display direction by means of the user input unit 110, and select the image display direction for the image display unit 150.
As shown in FIG. 2, even though the upside and the downside of the image display unit 150 are actually exchanged, the up and the down locations of the image displayed on the image display unit 150 are not exchanged to show the image in a normal direction.
However, in case that a user should reset the image display direction according to the installation state of the image display unit 150, there exists an inconvenience that the user should readjust the image display direction every time the installation state of the image display unit 150 is changed.
In addition, in case that the tilted degree of the image display unit 150 is not exactly caught, there exists a disadvantage of taking many times of trials and errors until the image is displayed on the display screen in a normal direction.
Accordingly, the present invention has been devised to obviate the aforementioned drawbacks.
An object of the present invention is to provide a display device capable of automatically controlling the image display direction in which when slope of the display device is changed, the image display direction is automatically reset to be matched with the changed slope, e.g., the rotational angle of the display device, thereby enabling more convenient use of the display device.
In particular, even if the display device is turned upside down, the image displayed on the display device is normally displayed without being turned upside down.